UA124982C2 - A method for manufacturing a thermally treated steel sheet - Google Patents

Abstract

The present invention relates to a method for manufacturing a thermally treated steel sheet.

Description

The invention relates to a method of producing heat-treated sheet steel with a Piachet microstructure on an assembly line for heat treatment. The invention, in particular, can be applied in the field of production of motor vehicles.

As you know, sheet steel with an open surface or with a coating is used for the production of motor vehicles. Many grades of steel are used in the production of vehicles. The choice of steel grade depends on the final application of the steel part. For example, IS steels (which do not contain insertion elements) can be produced for parts exposed to external influences, TKIR steels (with ductility induced by transformation) can be produced for seats and cross members of the floor or front struts and YOR steels (two-phase) can to be produced for rear rail guides or transverse elements of the roof.

During the production of these steels, to obtain the desired parts with special mechanical properties for any specific application, the steels are subjected to very important types of processing. Such treatments can be, for example, continuous annealing before the deposition of a metal coating or quenching with redistribution of carbon. In such treatments, an important role is assigned to the cooling stage, since the microstructure and mechanical properties of steels mainly depend on the performance of the cooling treatment. Usually, the intended treatment, including the cooling stage, is selected from the list of known treatments, while such treatment is selected depending on the grade of steel.

The patent application MO 2010/049600 refers to a method of using a plant for heat treatment of a continuously moving steel bar, which includes the stages of selecting the cooling rate of the steel bar depending on, among other things, the metallurgical indicators at the entrance and the metallurgical indicators required at the exit from the installation; introduction of geometric characteristics of headquarters; calculation of the power transmission profile; determining the desired values of the control parameters of the cooling section and bringing the power transmission of the cooling devices of the cooling section into compliance with the specified control values.

However, this method is based only on the selection and application of known cooling cycles.

This means that there is a huge risk that for any one steel grade, e.g.

TVIR-steels, the same cooling cycle will be applied even in cases where each specific TKIR-steel has its own characteristics, including chemical composition, microstructure, properties, surface structure, etc. Thus, this method does not take into account the real characteristics of steel. This allows impersonal cooling of many grades of steel.

Therefore, such a cooling treatment is not adapted to this particular steel, and therefore at the end of the treatment, the desired properties will not be obtained. In addition, after processing, such steel can have a large dispersion of mechanical properties. Finally, even if it is possible to produce a wide range of steel grades, the quality of the cooled steel is insufficient.

Thus, the purpose of this invention is to overcome the above-mentioned shortcomings by proposing a method of production of heat-treated sheet steel, which has a special chemical composition of steel and a special microstructure, which is implemented on an aggregate line of heat treatment. This purpose in particular implies the execution of a cooling treatment adapted to each sheet steel, while such treatment is calculated very precisely in the shortest possible time in order to provide a heat-treated sheet steel with exceptional qualities, such as the minimum possible dispersion of properties .

This goal is achieved using the method according to item 1 of the claims. This method may also contain any signs according to paragraphs 2-35.

Another goal is achieved with the help of a roll according to clause 36 of the claims. This roll may also include signs according to para. 37 or 39.

Another goal is achieved with the help of the heat treatment line according to clause 40 of the claims.

Finally, this goal is achieved with the help of a computer software product according to item 41.

Other features and advantages of the invention will become apparent from the following detailed description of the invention.

To illustrate the invention, various embodiments and test samples will be described from non-limiting examples, in particular, with reference to the following figures.

Fig. 1 illustrates one example of a method according to the present invention.

Fig. 2 shows an example in which continuous annealing of sheet steel is performed, comprising a heating step, a holding step, a cooling step and an aging step.

Fig. C illustrates one preferred embodiment according to the invention.

Fig. 4 shows an example according to the invention in which sheet steel is continuously annealed prior to hot dip coating.

The terms are defined as follows: - SS: chemical composition in mass. 95, - Tamyuek: Target index of microstructure, - Tvizpaae: microstructure of the selected product, - Riade: target indicator of mechanical properties, - ti: initial microstructure of sheet steel, - X: fraction of phase in mass. 95, - T: temperature in degrees Celsius (C), - E: time (s), - 5: seconds, - OT5: ultimate tensile strength (MPa), - 8: yield strength (MPa), - metal coating on zinc-based means a metal coating containing more than 50 95 zinc, - aluminum-based metal coating means a metal coating containing more than 50 95 aluminum and - parameters of the heating process include time, temperature and rate of heating, - parameters of the aging process include time, temperature and the duration of exposure, - TRx, TRagapdaki and TRiauei contain time, heat treatment temperature and at least one element that is selected from: cooling, isotherm or heating rate, the value of the isotherm having a constant temperature, - SR; and SRhip contain time, temperature and cooling rate, and - nanofluids: liquid media containing nanoparticles.

The designation "steel" or "sheet steel" refers to a sheet, roll, or plate that has a composition that allows the part to reach a tensile strength of up to 2500 MPa and more preferably up to 2000 MPa. For example, the tensile strength is equal to or greater than 500 MPa, preferably equal to or greater than 1000 MPa, preferably equal to or greater than 1500 MPa.

A wide range of chemical composition is included, as the method according to the invention can be applied to any type of steel.

The invention relates to a method of producing heat-treated sheet steel that has a Pnade microstructure, THAT contains from 0 to 100 95 at least one phase selected from ferrite, martensite, bainite, pearlite, cementite and austenite, on an aggregate line of heat treatment containing a heating section , a holding section and a cooling section, which includes a cooling system, in which the thermal parameters of TRiasche are realized, while this method contains:

A. stage of preparation, which includes: 1) a sub-stage of selection, at which: a. and the chemical composition are compared to a list of predetermined products whose microstructure includes predetermined phases and predetermined fractions of phase content in order to select a product having a Tz-iapaach microstructure closest to PTiate and a TR-apaaach that contains at least, heating, holding and cooling stage to achieve IPch-iapoag, r. heating mode, holding mode, including Teoakipo holding temperature, WHEREAS, the cooling power of the cooling system and the cooling temperature of Tsosoip are SELECTED based on TRaapaag and 2) a calculation substep in which with the help of variation of the cooling capacity, new cooling regimes of CP»x are calculated, based on the product selected at stage A.1.a), as well as TReapaae, the initial microstructure of the sheet steel to achieve Piade, the heating mode and the holding mode containing Toakipo and Tsosipo, At the same time, the cooling stage of TR-iapdagi is recalculated using the specified CPx in order to obtain new thermal regimes TR,, among which each TR"; corresponds to a certain microstructure of tx, 3) the selection stage, in which one TRiades is selected for the achievement of Thiade, while TRiauei is selected from the calculated thermal regimes of TRx and is chosen so that tx would be the closest to Tiaroe,, and

B. stage of heat treatment, at which TR'agoe is realized on sheet steel..

Regardless of any specific theory, when applying the method according to this invention, it is possible to obtain in a short calculation time a personalized thermal, in particular, cooling mode for each one intended for processing 60 steel sheets. Indeed, the method according to this invention makes possible a precise and certain mode of cooling, which takes into account Piade, in particular, the proportion of the content of all phases during the cooling process and those (including the dispersion of the microstructure on the steel sheet). Indeed, the method according to this invention takes into account thermodynamically stable phases, i.e. ferrite, austenite, cementite and pearlite, as well as thermodynamically metastable phases, i.e. bainite and martensite, in the calculations. Thus, it turns out to be possible to obtain sheet steel that has the expected qualities with a minimal spread of properties. Preferably, the TR-Apaach contains, in addition, a stage of preheating.

Preferably, the TReaapaach, in addition to this, includes a step of applying a hot dip coating, an aging step and a relaxation step or a step of forming a mixed structure during the redistribution of carbon.

It is preferable to obtain a microstructure of thiate: contains: - 100 Fo austenite, - from 5 to 95 95 martensite, from 4 to 65 95 bainite with another that is ferrite, - from 8 to 30 95 residual austenite, from 0.6 to 1 .5 95 carbon in a solid solution with another that is ferrite, martensite, bainite, pearlite and/or cementite, - from 1 95 to 30 95 of ferrite and from 1 95 to 30 95 of bainite, from 5 to 25 95 of austenite with another, which is martensite, - from 5 to 20,956 residual austenite with other, which is martensite, - ferrite and residual austenite, - residual austenite and intermetallic phases, - from 80 to 100 95 martensite and from 0 to 20 95 residual austenite, - 100 to martensite, - from 5 to 100 95 of pearlite and from 0 to 95 95 of ferrite, and - at least 75 95 of equiaxed ferrite, from 5 to 20 95 of martensite and bainite in an amount less than or equal to 10 95.

Preferably, during sub-step A.1) of selection, the chemical composition and Thiade are compared with a list of predefined products. In advance, certain products can be steel of any grade.

For example, they include two-phase steel (OR), steel with ductility induced by transformation (TKIIR), steel with quenching and redistribution (08P), steel with ductility caused by twinning (TUMIR), carbide-free bainite steel (SEV) hardened under a press

Zo steel (RN5), triplex (TKIRIEH), duplex (ORI EX) and highly plastic two-phase steel (OR NO).

The chemical composition depends on each sheet steel. For example, the chemical composition of SS steel may contain: 0.05 "C" 0.3 9, 0.5 x Mn x 3.0 9;

Хх 0.008 95;

Р x 0.080 95,

M 01 year; milestone 1.0 96, the rest in the composition is represented by iron and inevitable impurities that appear during production.

Each predetermined product has a microstructure that includes predetermined phases and a predetermined phase content ratio. Preferably, the predetermined phases at stage A.1) are limited to at least one element selected from the size, shape and chemical composition. Thus, IPeopoise includes predetermined phases in addition to predetermined phase ratios. Preferably those, p7x, Pnade include phases limited by at least one element selected from size, shape and chemical composition.

According to the invention, a pre-determined product is selected that has a microstructure of Teaiapaaga closest to ITiagde, as well as TReaapaae TO ACHIEVE IPeiapaayum. At the same time, Peapoagi contains the same phases as Thiagoei. Mostly PTziapaag also contains the same phase ratios as Thiagoei.

Fig. 1 illustrates an example according to the invention, in which the sheet steel intended for processing has the following SS (chemical composition) in mass percentages: 0.2 95 C, 1.7 U Mn, 1.2 95 5i and 0.04 95 AI. tiade contains 15 95 residual austenite, 40 95 bainite and 45 95 ferrite, from 1.2 95 carbon in solid solution in the austenite phase. According to the invention, SS and tiaude are compared with a list of predetermined products selected from the number of products 1-4. SS and other correspond to product C or 4, while such product is TKIR steel.

Product C has the following SSz in terms of mass percentages: 0.25 95 C, 2.2 95 Mp, 1.595 5i ii 0.04 ФХ АХ. tz, corresponding to TR", contains 12 95 residual austenite, 68 95 ferrite and 20 95 bainite, from 1.3 96 carbon in solid solution in the austenite phase.

Product 4 has the following SS: in terms of mass percentages: 0.19 95 C, 1.8 95 Mp, 1.2 95 5i and 0.04 Ф А. and, corresponding TRa, contains 12 95 residual austenite, 45 95 bainite and 43 95 ferrite, from 1.1 96 carbon in solid solution in the austenite phase.

Product 4 has a microstructure that is closest to nate, as it contains the same phases as and

Drink more, and in the same proportions. As shown in Fig. 1, two predetermined products may have the same SS chemical composition and different microstructures. Indeed, the Product and

Product: both are YUR 600 steels (two-phase, having an OT5 of 600 MPa). One difference is that Product: has a microstructure of ti, and Product: has a different microstructure of t". Another difference is that Product: has an index of 5, which is 360 MPa, and Product: has a UZ of 420

MPa Thus, it turns out to be possible to obtain sheet steel with a different OT5/U5 ratio for one steel grade.

Then, based on TRaptayuch, the cooling capacity of the cooling system is selected to provide the heating mode, the holding mode, including the holding temperature 1 -oakipo and the cooling temperature 1 esoooiipo.

In the course of sub-stage A.2) of calculations, in which, when varying the cooling capacity, new cooling regimes SRx are calculated, based on the product selected in stage A.1.a), as well as TRaapoae, microstructure for achieving Thiade, heating mode and holding mode, which contains Toakipo and Hsooiipo. In this case, the cooling stage TReaatmas is recalculated using the indicated SR" in order to obtain new thermal regimes TR", among which each

TRx corresponds to a certain microstructure of thx. When calculating CPx, the behavior during thermal exposure and the metallurgical properties of sheet steel are taken into account, unlike standard methods, in which only the behavior during thermal exposure is considered. In the example in Fig. 1, product 4 is selected, since and is the closest to Piade, while and and TR. correspond, Piziapoaga Y T Reiapaaga.

Fig. 2 illustrates a continuous annealing of sheet steel comprising a heating step, a holding step, a cooling step and an aging step. A set of SR" is calculated so as to obtain new thermal regimes TR." and accordingly one TRiagoe!.

Mostly at stage A.2) the cooling capacity of the cooling system varies from the minimum to the maximum value. The cooling capacity can be determined by the flow rate

From the coolant, the temperature of the coolant, the nature of the coolant and the heat exchange coefficient, while such a liquid can be both a liquid and a gas.

In another preferred embodiment, the cooling capacity of the cooling system varies from a maximum to a minimum value.

For example, the cooling system includes at least one jet cooling, at least one spray cooling, or at least both. Preferably, the cooling system contains at least one jet cooling, while such jet cooling sprays the fluid medium, which is a gas, an aqueous liquid, or a mixture thereof.

For example, the gas is selected from air, NM», H», M», Ag, He, water vapor or their mixture. The water-containing liquid is selected, for example, from water or nanofluids.

Preferably, jet cooling sprays gas with a flow rate between 0 and 350,000

Nm/h The number of cooling nozzles present in the cooling section depends on the aggregate heat treatment line and can vary from 17 to 25, preferably from 1 to 20, preferably from 1 to 15 and more preferably between 1 and 5. The flow rate depends on the number of cooling nozzles . For example, the flow rate of one cooling nozzle is between 0 and 50,000 Nm/h, preferably between 0 and 40,000 Nm/h, more preferably between 0 and 20,000 Nm3/h.

In the case where the cooling section contains cooling nozzles, the change in cooling capacity is based on the flow rate. For example, for one cooling jet 0 Nmz/h. correspond to the cooling capacity of 0 95 and 40000 Nm3/h. corresponds to a cooling capacity of 100 95.

Thus, the cooling capacity of one cooling jet varies from 0 Nm3/h, i.e. 0 95, to 40000 Nm3/h, i.e. 100 95. The minimum and maximum value of the cooling capacity can be any value selected in the range from 0 to 100 9". Such a minimum value corresponds to, for example, 0 95, 10 Fo, 15 9Uo or 25 95. For example, the maximum value is equal to 80 95, 85 95, 90 95 or 100 9.

In the case where the cooling section contains at least 2 nozzles, the cooling capacity of each cooling nozzle may be the same or different. This means that each cooling jet can be formed independently of the other. For example, when the cooling section contains 11 cooling nozzles, the cooling capacity of the first three cooling nozzles can be 100,956, the cooling capacity of the next four can be 45,95, and the cooling capacity of the last four can be 0,95.

The change in cooling capacity has an increment of, for example, between 5 and 50 95, preferably between 5 and 40 95, more preferably between 5 and 30 95 and preferably between 5 and 20 95. The increment in cooling capacity is, for example, 10 95, 15 95 or 25 95.

In the case where the cooling section contains at least 2 nozzles, the cooling power gain on each nozzle can be the same or different. For example, at the stage

A.2) the increase in cooling capacity can correspond to 5 95 on all cooling nozzles. In another embodiment, the increase in cooling capacity can be equal to 595 for the first three nozzles, 20 o for the next four and 15 o for the last four. Mostly, the increase in cooling capacity of each cooling nozzle is different, for example, 5 95 for the first nozzle, 20 95 for the second nozzle, 0 95 for the third nozzle, 10 95 for the fourth nozzle,

About 95 for the fifth nozzle, 35 9o for the sixth nozzle, etc.

In one preferred embodiment, the cooling systems are configured depending on the phase transformation in an independent manner. For example, when the cooling system contains 11 cooling nozzles, the cooling capacity of the first three cooling nozzles can be configured to effect the transformation, the cooling capacity of the next four can be configured to provide the transformation of austenite to pearlite, and the cooling capacity of the last four can be configured to transform austenite to bainite. In another embodiment, the increase in cooling capacity may differ when each cooling nozzle is connected.

Preferably at stage A.1.5) T»eoakpo Is a fixed value chosen in the range between 600 and 1000 "C. For example, T-oakipdo in Dependence on sheet steel can be equal to 700 "C, 800 "C or 900 s.

In another preferred embodiment, T»oakpo varies from 600 to 1000 "C. For example, Tweoakio MAY, depending on the sheet steel, vary from 650 to 750 "C or from 800 "C to 900 "C.

Preferably, when Teoakpo Changes after step A.2), a further sub-step of calculations is performed so that: p. Theoakipda Vary from the value in a predetermined range, choose from 600 to

Koo) 1000 "C, and a. for each change in Theoaklo, new cooling regimes SRx; are calculated, based on the product selected at stage A.1.a) and TRaatai, the initial microstructure of the sheet steel for

ACHIEVING IPviapaami and Tsooiiipo, AT TsooOMu the stage of cooling TRchaaptaa is calculated again using the specified CPx in order to obtain new thermal regimes of TRx with the fact that each TRx corresponds to the microstructure of thx.

Indeed, with the method according to this invention, changes in T»oakpo are taken into account during the calculations of SRx. Thus, for each holding temperature, many new SR modes are calculated.

Preferably, at least 10 SRs are calculated, more preferably at least 50, preferably at least 100 and more preferably at least 1000. For example, the number of calculated SRs is between 2 and 10,000, preferably between 100 and 10,000, more preferably between 1,000 and 10,000.

At stage A.3) one TRiade is selected to achieve the TTiade, while the TRiade is selected from among the calculated TRs, and is chosen so that 6 is closest to the Tiayue. Mostly the differences in the phase ratios present in ITPiaue and th cSKLadayut x 3 95.

Preferably, when at least two TRx have the same thx, the TR is selected, which has the minimum required cooling capacity.

Preferably, when T"eoakipa IS VARIABLE, the selected TReaatjei, in addition, includes the value of T"-oakipa TO achieve TPiatei), WHEREIN TRiamde is selected from TR.

Preferably at stage A.2) thermal enthalpy H released between ti and Tiage is calculated as follows:

N is released - (Xferite x Nfrerite) n (Chmartensit x Nmartensit) n (Hbeinite x Nbeinite) n (Xperlite x Nperlite) n (Nuementite n Xcementite) n (Naustenite n Haustenite), while X is the phase fraction.

Regardless of any particular theory, H represents the energy released during the entire thermal process when the phase transformation takes place. It is assumed that some phase transformations are exothermic and some are endothermic. For example, the transformation of ferrite to austenite during the heating process is endothermic, while the transformation of austenite to pearlite during the cooling process is exothermic. because In one better embodiment, at stage A.2), the entire thermal cycle SR" is calculated as:

and ZA) - т щ (Fonvective Ya. Frvyiminyuyusya) li ne Releases r. Er! Sre Sre de Sre - specific heat capacity of the phase (J'kg!-K7), p - steel density (g:m3), Er - steel thickness (m), F - heat flow (convective and radiative in W), Not released (J'Kg"), ТТ - temperature of ССО) its - time (s).

Preferably, at stage A.2), at least one intermediate microstructure of steel, corresponding to the intermediate thermal regime SR»hip, and thermal enthalpy are calculated. In this case, the results of calculating SRx are determined from the calculation of the set of SRhip. Thus, mostly

SRx is the sum of all SRhim and Nueezeee - the sum of all Nhia. In this preferred embodiment, SRhip is calculated periodically. For example, it is calculated every 0.5 seconds, preferably 0.1 seconds or less.

Fig. C illustrates one preferred embodiment in which in step A.2) tipi and Pip, respectively, SRhipn and SRhime, as well as Nhipn and Nhile are calculated. During the implementation of the entire thermal regime, Neeveazea is determined to calculate SRx. In this embodiment, a plurality, i.e., more than two, SR.»ip, Thiti Nhit to obtain SR» (not shown) may be calculated.

In one preferred embodiment, prior to step A.1), at least one target Riade mechanical property IS selected from yield strength 5, ultimate tensile strength

OT5, lengthening, distribution of the hole, molding. In this embodiment, it is mainly calculated

Piagoei based on Riate.

Regardless of any particular theory, it is assumed that the characteristics of sheet steel are determined by the technological parameters used in the steel production process.

Thus, mainly at stage A.2) to calculate SR" the technological parameters of the processing method to which the steel sheet is subjected before entering the heat treatment line are taken into account. For example, the parameters of the method include at least one element, which is selected from the degree of crimping during cold rolling, the temperature of winding into a roll, the mode of cooling on the output roller mill, the cooling temperature and the speed of cooling of the roll.

In another embodiment, when calculating SRx, the technological parameters to which the sheet steel will be exposed on the heat treatment line are taken into account. Such parameters include, for example, at least one element that is selected from the speed of the line necessary to achieve a specific steel sheet temperature, the thermal power of the heating sections, the heating temperature and the holding temperature, the cooling capacity of the cooling sections, the cooling temperature, the aging temperature.

In the case where the cooling section is followed by a hot coating section, 1 esoiiipu is preferably the temperature of the bath containing the dip melt. Mostly, the melt in such a bath is based on aluminum or zinc.

In one preferred embodiment, the aluminum-based bath contains less than 15 95 51, less than 5.0 95 Re, optionally from 0.1 to 8.0 95 Mao, and optionally from 0.1 to 30, 0 95 7p with another, there is AI.

In another preferred embodiment, the zinc-based bath contains 0.01-8.0 90 AI, optionally 0.2-8.0 956 Mo with another that is 2p.

The molten bath may also contain unavoidable impurities and residual elements that appear from the loaded ingots or as a result of the passage of sheet steel through the molten bath. Optional impurities are selected, for example, from 5g, ZB, RB, Ti, Ca, Mp, 5p, Ha,

Se, St, 2g or Vi, while the mass fraction of each additional element is less than 0.3 mass. 96. Residual elements from loaded ingots or those that appear as a result of passing through a bath with molten sheet steel can be iron with a content of up to 5.0 wt. 95, Mostly 3.0 wt. 95.

In another preferred embodiment, Tsooipo Is the quenching temperature Ta. Indeed, for letter

OgvR-steel Ta is an important parameter of hardening and redistribution.

Mostly Tooipo is located between 150 and 800 "C.

Preferably, every time a new steel sheet enters the heat treatment line, a new stage of A.2) calculations is automatically performed based on stage A.1) of the selection made in advance. Indeed, the method according to the present invention adapts the cooling regime for each sheet of steel, even if the same grade of steel enters the heat treatment line, since the actual characteristics of each steel often differ. New sheet steel can be detected and new sheet steel features are measured and pre-set.

For example, a sensor detects a weld between two rolls, Figure 4 illustrates an example according to the invention in which sheet steel is continuously annealed prior to hot dip coating. In the method according to the present invention, after selecting a predetermined product having a microstructure close to Thyatea (not shown), CPx is calculated based on t, the selected product and Pade. In this example, intermediate thermal regimes are calculated from SRhipna to SR»ipnz, corresponding, from Ihipna TO IPhipiz and From

Nhipy to Nuhipz. Nuezaizeeo is defined for the purpose of receiving SR; and, hence, TRx. This Figure illustrates TRiagoe.

With the help of the method according to this invention, the step of heat treatment is performed, in which TRiage is implemented on the steel sheet.

Thus, a roll is obtained, which is made of sheet steel, including the specified predetermined types, which include ОР, ТКИР, О8Р, ТУМР, SЕВ, РН5, ТКИРИ ЭХ, ВОРИ ЭХ, ОР

BUT, at the same time, such a roll exhibits a standard deviation of mechanical properties between any two points on the roll equal to or below 25 MPa, preferably equal to or below 15

MPa, more preferably equal to or below 9 MPa. Indeed, regardless of any particular theory, it is assumed that this method, which includes step A.2) of the calculation, takes into account the dispersion of the microstructure of sheet steel along the roll. Thus, applied at this stage to sheet steel TRizschsheye makes it possible to homogenize the microstructure, as well as mechanical properties. Preferably, such mechanical properties are selected from 5, OT5 or elongation.

The low value of the standard deviation is due to the accuracy of TRiagoea.

Preferably, a zinc-based or aluminum-based metal coating is applied to the roll.

Preferably, in industrial production, the standard deviation of the mechanical properties between 2 rolls made of sheet steel, including the specified predetermined types, including ОР, ТКИР, 0 8 Р, TUMIR, SEV, РН5, ТКИРИ ЭХ, ЮОРИЭХ, ОР НО, is successively measured at of the same line, is equal to or less than 25 MPa, preferably equal to or less than 15 MPa, more preferably equal to or less than 9 MPa.

A heat treatment line is used to implement the method according to this invention in order to implement TRizayue. For example, such a heat treatment line is a continuous annealing furnace.

A computer software product containing at least one metallurgical module, a thermal module and an optimization module interacting with each other is used to determine TRiade, and such modules contain program instructions that, when executed by a computer, implement the method according to this invention .

The metallurgical module predicts the microstructure (Pich, Thiade, including metastable phases: bainite and martensite and stable phases: ferrite, austenite, cementite and pearlite), and, more precisely, the fractions of phase content throughout the processing time, and also predicts the kinetics of phase transformation.

The thermal modulus predicts the temperature of the sheet steel depending on the installation used for heat treatment, such an installation being, for example, a continuous annealing furnace, the geometric features of the staff, the parameters of the method, including the cooling power, heating or the value of the isotherm, the thermal enthalpy H, which is released or consumed during the entire time of implementation of the thermal regime during the phase transformation.

The optimization module determines the best thermal regime for achieving Tiaoeya, i.e. TRiagdea according to the method of the invention using metallurgical and thermal modules.

Further, the invention is explained with reference to experimental data, which are provided solely for informational purposes. They are not restrictive.

Example.

In this example, OR 780 SI was chosen, which has the following chemical composition:

And ola5 | 18 | 02 | 02 | 00025 | 0015 | 002 | 0025 | 006

Cold rolling was applied with a compression ratio of 50 96 to achieve a thickness of 1 mm.

The desired payuev contains 1395 martensite, 4595 ferrite and 42 95 bainite, corresponding to the following Rather: UZ 500 MPa and SHT5 780 MPa. A T'ooipo cooling temperature of 460 "C must also be achieved to perform dip coating in the zinc bath. To ensure good acceptability of the coating in the 7p bath, this temperature must be achieved to within w/- 2 76.

First of all, a given sheet steel was compared with a list of predetermined products in order to obtain a selected product having a T»apaas microstructure closest to Tiage!.

The selected product was also ОР78ООІІ, which has the following chemical composition:

The microstructure of OR78OSII, i.e. eapaae, contains 1095 martensite, 50 95 ferrite and 40 95 bainite. The appropriate thermal regime of TR-azplaaa is as follows: - the pre-heating stage, in which the sheet steel is heated from the ambient temperature to 680 "C for 35 seconds, - the heating stage, in which the sheet steel is heated from 680 "C to 780 "C for 38 seconds, - the holding stage, in which the sheet steel is heated at a holding temperature of 780 °C for 22 seconds, - the cooling stage, in which the sheet steel is cooled with the help of 11 cooling nozzles that spray NM", as follows: / Forsuuki (m) | 1 | 2 | with | 4 | 5 | 6 | 7 | 8 | 9 | yu | "

Speed

Power shoodenyasyu | 2 | 010000 vv || then | оо) tov - coating by immersion in a bath with molten zinc at 460 "C, - cooling of sheet steel for 24.6 s at ЗО0 "Си - cooling of sheet steel at ambient temperature.

Next, a number of cooling regimes of SRx were calculated, based on the selected product and ОР78ОСИ and belonging to ОР78О ТРаааае, those to achieve Pyaude, heating mode, holding mode, which includes T -oakipd | 1 sooiipo.

The stage of cooling TRchapiaach was recalculated using the specified SRx to obtain new thermal regimes of TRx. After calculating ТР», one TRiade was selected to achieve Tiagea, At the same time, TRiade was chosen among the calculated ТР,;, and was chosen so that th would be closest to Тtiagea, and TRiade was as follows: - preheating stage, in which the sheet steel is heated from the ambient temperature to 680 "C for 35 seconds, - the heating stage, in which the sheet steel is heated from 680 "C to 780 "C for 38 seconds, - the holding stage, in which the sheet steel is heated at the holding temperature T -oakipo 780 " C for 22 seconds, - cooling stage SR", containing: / Force units (m) | 1 | 2 | with | 4 | 5 | 6 | 7 | 8 | 9 | yu | "

Cooling speed 912 7 zav 7 v

Power shoodenyasyu | 2 | 0 0 | about || - application of coating by immersion in a bath with molten zinc at 460 "С, - cooling of sheet steel for 24.6 s at ЗО0 "Si - cooling of sheet steel at ambient temperature.

Table 1 shows the properties obtained on sheet steel with TR aapoak and TRiage!:

Expected nn and S Ya

Microstructure obtained in Chmartensite: 12.83 o Chmartensite: 12.86 o Chmartensite: 13 95 end of the thermal regime Hoerite: 53.85 o Hoerite: 47.33 o Hoerrite: 45 95

Hbeinite: 33.31 o Hbeinite: 39.82 o Hbeinite: 42 o - - Chmartensite: 0.17 90 Chmartensite: 0.14 96

In V. Y

Khbeinite: 8.69 o Khbeinite: 21 8 o (Deviation U5 in relation to Rase(MPa) | 66 | 6 | -

Bin PINKY PNO ON NOV 14

Riage «MPa)

With the help of the method according to this invention, it is possible to obtain sheet steel that has the desired expected properties due to the fact that the thermal regime TRiaschshee is adapted to each sheet steel. On the contrary, in the case of using the standard thermal mode TR-iapaaa, the expected properties cannot be obtained.

Claims (1)

FORMULA OF THE INVENTION 1. Method for the production of heat-treated sheet steel having a Thiage microstructure, WHICH contains at least one of the phases selected from ferrite, martensite, bainite, pearlite, cementite and austenite, in a heat treatment line comprising a heating section, a holding section and a cooling section , which includes a cooling system, at the same time providing a thermal regime TRiaue), while the specified method includes: A) a preparation stage, which includes: 1) a selection substage, in which: a) The falls and the chemical composition are compared with the list of predetermined products , the microstructure of which includes predetermined phases and predetermined fractions of the phase content, to select a product that has a Pviapaae microstructure closest to Pnayue, and TReapaae, WHICH includes at least a heating, holding and cooling stage to achieve tsiapaage, B) based on TRaapaache, choose heating mode, holding mode, including holding temperature Theoaklo, COOLING capacity of the cooling system and cooling temperature Tsooii by, and 2) a sub-stage of calculations, in which, with the help of changing the cooling capacity, new modes of cooling SRx are calculated, based on the product and TRaapaay, the OUTPUT microstructure t, selected at stage A.1.a). of sheet steel to achieve Tiaoe), the heating mode and the holding mode, which includes Tvoakipa and Tsosoipo, WHEREAS, the cooling stage TRaapaachie is calculated again using the specified CPx to obtain new thermal regimes TRx, and each TRx corresponds to a certain microstructure thx, Zo 3) selection stage , in which one Triadee is chosen TO ACHIEVE Tiayue, At the same time TRIayue! choose from the calculated thermal regimes ТРх so that тх would be the closest to tiauei, and B) stage of heat treatment, at which 1 Riage! is carried out for sheet steel. 2. The method according to claim 1, in which the predetermined phases at stage A.1) are determined by at least the following parameters: size, shape and chemical composition. 3. The method according to claim 1 or 2, in which the reheater also includes a preheating step. 4. The method according to any one of claims 1-3, in which TReaptasd also includes a step of applying a hot dip coating, an aging step and a vacation step or a step of forming a mixed structure. 5. The method according to any of claims 1-4, in which the microstructure of the taughey contains: 100 95 austenite or from 5 to 95 95 martensite, from 4 to 65 95 bainite and other ferrite, or from 8 to 30 956 residual austenite, 0.6 to 1.5 956 carbon in solid solution with other being ferrite, martensite, bainite, pearlite and/or cementite, or 1 to 30 95 ferrite and 1 to 30 95 bainite, 5 to 25 95 austenite with other martensite, or 5 to 20 95 retained austenite with other martensite, or ferrite and retained austenite, or retained austenite and intermetallic phases, 80 to 100 95 martensite and 0 to 20 95 residual austenite, or 100 95 martensite, or from 5 to 100 95 pearlite and from O to 95 95 ferrite, or at least 75 95 equiaxed ferrite, from 5 to 20 95 martensite and bainite in an amount less than or equal to 10 95. 6. The method according to any one of claims 1-5, in which said predetermined types of products include two-phase steel, steel with ductility induced by transformation, steel with hardening and redistribution, steel with ductility due to twinning, carbide-free bainite steel, press-hardened steel, triplex, duplex and highly plastic two-phase steel. 7. The method according to any of claims 1-6, in which at stage A.2) the cooling capacity of the cooling system is changed from the minimum to the maximum value. 8. The method according to any of claims 1-6, in which at stage A.2) the cooling capacity of the cooling system is changed from the maximum to the minimum value. 9. The method according to any of claims 1-8, in which at stage A.1.0) Theoaklo IS a fixed value selected in the range from 600 to 1000 "С. 10. The method according to any of claims 1-8, in which at stage A.1.B) Tesakpo is CHANGED from 600 to 1000 "C. 11. The method according to claim 10, in which the following sub-step of calculations after stage A.2) is performed as follows: c) Tvoakpo is changed from a value in a predetermined range, selected from 600 to 1000 "С, и Я) for each change of T»oakpo New modes of cooling CPx are calculated, based on the product selected at stage A.1.a) and TRaapayu, the OUTPUT microstructure of the sheet steel to achieve Pchiapaag and Zo Tsosipo, while the stage of TRvapayu cooling is calculated again using the indicated CPx to obtain new thermal regimes of TRx , while each TRx corresponds to the microstructure of th. 12. The method according to claim 11, in which at the stage of selection A.3) the selected TRiaschei also contains the value of T oakipo. 13. The method according to claim 12, in which at stage A.3), when at least two ТР» have the same тх, the ТРiaue, which has the minimum required cooling capacity, is selected. 14. The method according to any one of claims 1-13, in which at stage A.2) the difference between the ratios of the phases present in Tiayue and tx is equal to 95. 15. The method according to any of claims 1-14, in which at stage A.2) the thermal enthalpy H released between ti and Pagde is calculated as follows: In (Hbeinite" Nbeinite)--(X pearlite" Nperlite)-(NcementiteX cementite) we (Naustenite Haustenite), WHERE X is the phase fraction. And, fall; zar Z, (brazhamm vane and odnayams LOVI NnKlSVh are calculated as: p: Er and Se C re de Sre - specific heat capacity of the phase (J'kg".K7),, p - density of steel (gm), Er - thickness of steel (m ), Ф - heat flow (convective and radiative in W), T - temperature of SS) and - time (s), Nreleased - Heat enthalpy released between ti and Tiage (J kg). 17. The method according to any one of claims 15 or 16, in which at stage A.2) at least one intermediate microstructure of thip steel, corresponding to the mode of intermediate cooling CPhim, and thermal enthalpy Н»hip are calculated. 18. The method according to claim 17, in which at stage A.2) SRx represents the sum of all SRhit, Neeieagea IS THE SUM of all Nhip. 19. The method according to any one of claims 1-18, in which before step A.1) at least one target mechanical property (Riaude) selected from yield strength 5, tensile strength OT5, elongation, hole distribution and formability is selected. 20. The method according to claim 19, in which Thiade is calculated based on Riagoe!. 21. The method according to any of claims 1-20, in which at stage A.2) to calculate SRx, technological parameters of the processing process to which sheet steel is subjected before entering the heat treatment line are taken into account. 22. The method according to claim 21, in which the parameters of the method include at least one element selected from the degree of crimping during cold rolling, the temperature of winding into a roll, the mode of cooling on the output roll, the temperature of cooling and the speed of cooling of the roll. B 23. The method according to any of claims 1-22, in which at stage A.2) to calculate SRx, the technological parameters of the processing process to which sheet steel is subjected in the heat treatment line are taken into account. 24. The method according to claim 23, in which the parameters of the specified process include at least one of the following parameters: the temperature required for the heat treatment of each particular sheet steel, the line speed, the cooling capacity of the cooling sections, the thermal power of the heating sections, the aging temperature, the cooling temperature, the heating temperature and holding temperature. 25. The method according to any one of claims 1-24, in which the cooling system comprises at least one jet cooling, at least one spray cooling, or at least both. 26. The method according to claim 25, in which, in the case when the cooling system contains at least one jet cooling, such jet cooling atomizes a gas, an aqueous liquid, or a mixture thereof. 27. The method according to claim 26, in which the gas is selected from air, NMx H», M», Ag, He, water vapor or their mixture. 28. The method according to claim 27, in which the water-containing liquid is selected from water or nanofluid. 29. The method according to claim 27, in which the stream sprayed by the cooling nozzle has a flow rate of 0 to 350,000 Nm3/h. 30. A method according to any one of claims 1-29, in which Tsooiluo IS the temperature of the bath when the cooling section is followed by a hot dip coating section containing a hot dip bath. 31. The method according to claim 30, in which the melt bath is formed on the basis of aluminum or zinc. 32. The method according to any one of claims 1-29, in which Teooipo is the quenching temperature Tu. 33. The method according to any one of claims 1-32, in which Tsooipo is from 150 to 800 "S. 34. The method according to any one of claims 1-33, in which, during the arrival of new - sheet steel on the heat treatment line, a new stage A.2) is automatically performed, based on the previously performed stage A.1) of selection. 35. The method according to claim 34, in which adaptation of the cooling mode of sheet steel is carried out when it enters the cooling section of the heat treatment line on the first meters of the sheet.